Fast National ratings for Tuesday, May 29, 2012Facing less competition now that the main TV season has ended, "America's Got Talent" posted its best ratings this year on Tuesday night, leading NBC to a victory among adults 18-49. Elsewhere, ABC got solid numbers for a "20/20" special on Queen Elizabeth II, and "Cougar Town" ended its run on the network with a small bump over its most recent airing. The CW's new unscripted series "The Catalina" didn't make much noise, falling just short of a million viewers.CBS led the night in viewers with 7.6 million and a 5.0 rating/8 share in households. NBC (7.5 million, 4.6/7) finished a close second, and ABC took third with 5.7 million viewers and a 4.0/6. FOX (2.3 million, 1.5/2) came in fourth. The CW averaged 810,00 viewers and a 0.5/1.NBC led the 18-49 demographic with a 2.3 rating. CBS grabbed second with a 1.4, followed by ABC at 1.3....